Polished turbine fuel

ABSTRACT

Turbine fuel provided for large-scale land based turbines used by utilities for producing electricity and desalinated water, and for large mobile engines and turbines in marine and remote applications where only liquid fuels are available. Use results in less corrosion, ash formation and emissions (NOx, SOx, CO2 and noxious metals) than firing contaminated heavy crude, refinery residual oils or high sulfur fuel oils. Manufacture is by decontaminating crude oils, non-conventional crudes, and other highly contaminated feeds. Each fuel is produced as a single product of unit operations, not ex-plant blend of various refinery products, yet using an apparatus configuration less complex than conventional crude oil refining. These fuels can be fired by advanced high efficiency turbines of combined cycle power plants having hot flow paths and heat recovery steam generation systems susceptible to corrosion, which systems cannot otherwise risk contaminated heavy crudes or refinery residual oils feeds.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. Ser. No. 16/089,850 filed onSep. 28, 2018, which is a 371 National Phase of InternationalApplication Serial No. PCT/US2016/057536 filed on 18 Oct. 2016, both ofwhich are incorporated herein by reference.

FIELD OF THE INVENTION

The invention relates to decontaminated, ultraclean liquid fuel forcombustion gas driven turbines and processes and apparatus forproduction of such fuels from crude oils, refinery residual oils andother contaminated liquid feeds.

DETAILED DESCRIPTION

There is a need for improved methods to make low cost combustion gasturbine fuel from crude oils and other heavy liquids such as refineryresidual oils. There is also a need for inexpensive liquid turbine fuelwhich cause less or no turbine corrosion, fouling, and emissions.

Combustion gas driven turbines are widely used in various single cycleand combined cycle applications for large scale production of electricpower. Choice of fuel supply for turbine combustors determines overallplant efficiency, availability, and emissions.

Investment in large scale turbine driven power plants need certainty ofquantity and quality of fuel supply. Consumers and businesses demandreliable electrical supply from turbine driven sources.

Turbine degradation and failures due to fuel contamination relatedproblems are extensive. Contaminated fuels cause serious turbinefouling, corrosion and exhaust gas emissions issues. Massive equipmentfailures and extended disruption of electrical supplies to the grid andharm to the environment result from bad fuels.

To seek to avoid presence of contaminates, methane rich natural gas(NG), when available, is often selected as fuel by turbine designers.However, NG can contain entrained hydrocarbonaceous solids and othercontaminants such as hydrogen sulfide or carbonyl sulfide as well asair, water, and inert materials such as nitrogen and carbon dioxide thatimpact combustion. Also, methane escape raises environmental concernsamong some who estimate that methane has over twenty times the potentialimpact on alleged atmospheric warming than C02.

NG is often not available. Certain regions have limited or nosubstantial NG reserves or face prohibitive NG exploration, productionor transportation. Gaseous alternatives to NG such as liquefied naturalgas (LNG) and liquefied petroleum gas (LPG) might be considered but longterm uncertainties surrounding compression, storage, and shipment cancreate unacceptable investment risks for turbine driven operations.Similar factors apply to use of industrial waste gases such as blastfurnace gas, coke oven gas, refinery fuel gases or use of localnaturally derived liquids such as biofuels containing ethanol from corn,sugar canes and other plants or biodiesels from fats or other materials.

The reality is that “what are available at lowest cost” liquids are usedas turbine fuels when NG is unavailable or other alternatives cannotmeet supply requirements, even when such cause corrosion, fouling,operability and emissions problems. Turbine availability when fired oncrude oils or refinery residual oils does not match that of NG becauseof corrosion and ash formation.

For example, NG supply is extremely limited in the Hawaiian Islands, USAand in prior art literature, refinery residual oil is reported havingbeen used in Hawaii as turbine fuel. Also for various local reasons andpriorities, significant quantities of crude oils, refinery residual oilsor contaminated distillates are used as turbine fuels in certain regionsof the world such as Kingdom of Saudi Arabia, Kuwait, Iraq, parts ofAfrica.

However, energy efficiency has been sacrificed and fuel BTUs are wasted.Contaminated heavy liquid fuels are avoided for advanced classes ofhigher efficiency turbines, instead leaving only firing in less complexlower efficiency turbines. Also, such contaminated fuels are avoided forefficient combined cycle plants that allow exhaust heat recovery forstream generation; therefore, conversion of inefficient existing singlecycle plants using old art furnaces or turbines firing crude oils havenot been converted to more efficient combined cycle plants.

Contaminants within crude oil and residual fuels comprise, among others,various forms of sulfur, sodium, vanadium, calcium, silicon, nickel, andaluminum as well as particulate matter and carbonaceous materials suchas asphaltenes and other high molecular, highly viscous, tar-likeaggregates.

Contaminates lead to corrosion of hot gas path components. Presence ofsodium and sulfur leads to sodium sulfate which corrodes the turbine hotgas path metals. Other alkali metals within crudes or residuals such aspotassium can cause similar alkali-sulfate type corrosion and behavevery similar to sodium. Such attacks are often collectively referred toas ‘sulfidation’. Sulfidation is rapid in hot gas paths and evenrelatively low-sulfur fuels contain sufficient sulfur to enable hot zonecorrosion when alkali metals are also present. Corrosion by sulfidationcould be prevented by eliminating presence of all alkali metals but thatis not possible with prior art treatment processes for crude oils orresidual fuels.

Contaminates cause corrosion of combined cycle plants' heat recoverysteam generators (HRSG). Sulfur compounds react with oxygen to formsulfur dioxide, with subsequent oxidation to form sulfur trioxide.Sulfur trioxide reacts with water present to form sulfuric acid, whichcan condense during HRSG exhaust gas cooling. Sulfuric acid so formedcorrodes HRSG metals and other surfaces. Operating HRSG above dew pointtemperature minimizes heat recovery and decreases the thermal efficiencyof the power plant.

Contaminates lead to ash formation. Turbine combustion of crude oils orresidual oils containing contaminates such as vanadium, nickel, lead orzinc create metal oxide complexes which condense on turbine blades andinduce surface oxidation and deposits of ash. In the presence of sodiumor other alkali metals and oxygen, metals such as vanadium, lead or zinccreate mixed metal oxide complexes, for example vanadates of vanadium,lead or zinc. Such complexes may have relatively low melting points anddeposit as ash mixture and enhance turbine corrosion, whereas highermelting point complexes escape to atmosphere with the flue gas and donot stick to the Gas Turbine and HRSG components.

Contaminates that form ash particulate matter during burning causeoperating issues that require changes in HRSG materials of constructionas well as added apparatus, with related capital and operating cost. Forillustration, ash formation drives changes in HRSG related blowers andchanges in tubes and fins, that seek to reduce ash deposits or to reduceash collection on cooling surfaces.

Contaminates cause emissions. Presence of sulfur and combustor firingissues lead to formation of SOx, NOx and particulate matter emissions.Regulatory emission limits often reduce or eliminate liquid turbine fuelselections that are locally available.

Prior art fuel contaminants problems significantly reduce turbineup-time, maintenance cost, and power plant availability and causerepeated power outages.

Prior art efforts to ameliorate contaminate and ash formation problemsinclude:

-   -   (i) shutdown frequently, sometimes as often as weekly, for rapid        washing and other cleaning of affected combustors, blades, and        other hot zone elements.

However prior art discussions mention such frequent shutdown, cleaningand restart procedures cause turbines to suffer repeated thermal stress,metal fatigue shock, and excessive wear. Such brief periodic cleaningtypically does not allow sufficient downtime for major mechanicalrepairs or replacement of corroded or fouled parts;

-   -   (ii) necessity to store or have spare unit in ready status unit        for maintenance outage of affected corroded and fouled unit.

However, such spare systems are capital intensive and thus very rare.Also, significant costs are still incurred in restoring the affectedunit;

-   -   (iii) use of water wash fuel and addition of inhibitors at the        turbine site.

Such prior art treatments of contaminated liquid fuels include physicalwater washing and separation processes (such as centrifuges) seeking toremove those water-soluble contaminants that are readily dissolved orotherwise removed. Washing only addresses certain water-soluble alkalisalts and water-extractable particulate matter. The number of washingand separation stages depends on fuel quantity demand and on amount ofalkali content in each differing untreated fuel type, with a goal tomeet contract specifications for each treated fuel. Also, treatmentstypically include addition of expensive chemical inhibitors such asmagnesium, chromium or silicon compounds. The objective is to reduce thecorrosive effect and ash deposition caused by oil-soluble trace metalsthat remain in the fuel after washing and otherwise contribute to ashformation at combustion. The inhibitors seek to react with contaminatesand change the composition of the ash to increase its melting point tokeep the ash in solid form, thereby seeking to avoid ash melts anddeposits in the turbine.

In addition, such prior art treatments are not generic, instead eachtreatment process must be based on analysis of the untreated feed andcontract specification for each individual turbine, which is to use thetreated feed. Unexpected variations in feed, if not captured byanalysis, can cause major corrosion issues during small operatingintervals. Also, for large power generation facilities at high peak loadoperation, fuel feed requirements can be quite large and impose strainson limited treatment facilities.

-   -   (iv) combustion of distillate grade fuel oils, kerosene-type jet        fuel or other lighter liquid fuels.

However, this is an expensive alternative. These fuels are in highdemand and are produced primarily for the transportation market fortrucks, buses, airplanes, trains, marine, diesel autos and other mobileend-uses where alternatives are not readily available. In conventionalcrude oil refining, such fuel typically represent less than fortypercent of total production from each barrel of crude oil.

-   -   (v) combustion of lower cost residual fuel oils, such as those        used in furnaces and certain marine applications.

However, such increases contamination and resulting corrosion, ashformation and emissions. During conventional refining, contaminantsfound in crude oil feeds to distillation concentrate in distillationbottoms residuals instead of being removed from such residual oils. Thisconcentration mechanism leads to higher contaminant levels in refiningresiduals than initial crude oil feeds to refinery distillation sections

-   -   (vi) blending to reduce overall contaminant level and costs,        e.g. blend a lower cost heavier residual fuel oil having high        contaminate content with more expensive distillate having lower        levels of contaminant.

For example, in a description of a prior art combined cycle plant,refinery residual oil is tested when received and blended with No. 2diesel oil (as tested against specifications) to reduce the final blendused as turbine fuel to a maximum 2.75 percent sulfur then allowed bylocal permits. Basler, B. and Marx, D., 2001, “Heavy Fuel Operation atLimay Bataan Power Station,” Proceedings of ASME IGTI Turbo Expo, NewOrleans, La., ASME Paper No. 2001-GT-0213.

However, refinery residuals and distillate blend components are sold onspot markets. Each residual and distillate vary based on refineryconfigurations and their starting crude oil feed stocks. Fuel purchasersare unable to specify the crude and refinery source of the refineryresiduals and distillate blend components. Significantdelivery-to-delivery variations for each shipment are inevitable. Sothere are no consistent, uniform supplies of blends of residuals anddistillates for turbine fuel applications.

Analysis of each delivery of each such blend component shipment iscostly and sampling is logistically complex. Operating a blend plantwith significant variations in numerous differing compositions ofprospective blend components from different refineries and fromdifferent crude sources is a difficult task, given the need for arelatively stable fuel composition for combustor efficiency control andoptimization.

There is also a significant basic technical hurdle for blending.Blending different crude oil feed stocks or refinery residual oils fromderived from different crude oil feed stocks can disrupt naturalstabilization (e.g. blending highly aromatic with highly paraffiniccompositions). Resulting instability causes particles of asphaltenes andheavy resins to participate out of the blend and form deposits impactingstorage, feed piping, filters, turbine burner nozzles and otherapparatus.

Also, blending does not efficiently address contaminants left in theblends. Such contaminates remain to contribute to corrosion, ashformation and emissions.

The above background about fuel caused failures further confirms theneed to avoid direct firing in combustion gas turbines of crude oils andother heavy liquids such as refinery residual oils and confirms the needfor fuel causing less corrosion, fouling and emissions.

Conventional refining is described at section 2.1 of “Available andEmerging Technologies for Reducing Greenhouse Gas Emissions from thePetroleum Refining Industry”, the United States Environmental ProtectionAgency (US EPA). Such paper and references cited therein describeconventional crude distillation units (CDU) and other conventionalrefinery apparatus, operations, and slates of multiple products. Suchpaper states that “[t]here are three basic types of refineries: toppingrefineries, hydroskimming refineries, and upgrading refineries (alsoreferred to as “conversion” or “complex” refineries). Topping refinerieshave a crude distillation column and produce naphtha and otherintermediate products, but not gasoline. There are only a few toppingrefineries in the U.S., predominately in Alaska. Hydroskimmingrefineries have relatively mild conversion units such as hydrotreatingunits and/or reforming units to produce finished gasoline products, butthey do not upgrade heavier components of the crude oil that exit nearthe bottom of the crude distillation column. Some topping/hydroskimmingrefineries specialize in processing heavy crude oils to produce asphalt.Upgrading/conversion refineries have cracking or coking operations toconvert long-chain, high molecular weight hydrocarbons heavy fractionsinto smaller hydrocarbons that can be used to produce gasoline product,distillates, and other higher value products and petrochemicalfeedstocks.” As noted in such paper, to produce multiple refineryproducts, such conventional refining systems, have numerous costlyunits, are capital intensive and are expensive to power, operate andmaintain. The long standing approach in crude refining has been to focuson separation of crude into numerous product or product precursorstreams, instead of single product of crude, and processing suchnumerous streams in many downstream steps to make various grades ofgasoline, kerosene, diesel, jet aviation fuels, and feedstocks forchemicals production and then apply other heavily contaminated residualoils primarily for asphalt and coke production or in some regions toless environmentally friendly such as mazut or high sulfur fuel oils forfurnaces or marine applications.

“An Oil Refinery Walk-through”, American Institute of ChemicalEngineers, Chemical Engineering Progress May 2014, describesconventional refinery operations, including crude distillation units,wherein the “primary objective of the atmospheric crude fractionator isto separate the desalted crude oil (specified feed temperature) intofractions, or cuts, based on the boiling point ranges of thecomponents.” Such target cut-point ranges are based on temperatures anddo not change dictated by the final product specification, but flowrates must change if a different crude feed is used due to unit design.Each such side cut draw has a target initial boiling point and endboiling point to match capabilities of downstream units, for examplelight straight run naphtha, heavy straight run naphtha, kerosene/jetrange, light atmospheric gas oil, heavy atmospheric gas oil, andresidual oil or reduced crude fed to vacuum distillation unit. Only arelatively small portion of prior art cuts of each barrel of crude oilfeed are efficiently useful for turbine fuels, and not substantially theentire barrel. The crude oil distillation unit is the first processingunit in virtually all petroleum refineries. The crude distillation unitis often referred to as the atmospheric distillation unit orfractionator because it operates at slightly above atmospheric pressure.

Prior art processes for upgrading extra heavy crudes are not for turbinefuel production. Such processes have a general theme of feedingextremely poor quality crude into the process to upgrade the lessdesirable feed to more commercially desirable crude which can beprocessed in conventional refineries. These address converting highlyviscous oils from tar sands of Canada, from Monagas belt in Venezuelaand other sources to a synthetic or upgraded crude. Such are targeted tobetter compete with normal standard grades commercial crudes availableon worldwide markets. These converted materials are then offered toconventional crude refineries configured for crudes having normal ortypical ranges of crude viscosities, sulfur levels, and the like.Illustrative prior art includes Brown et al U.S. Pat. No. 4,885,080,references which cite Brown et al and those cited by Brown et al. Suchupgrading or synthetic crude process contemplate their productconsumption by conventional refineries and are not tailored for use incombustion gas turbines.

Such traditional approaches, confirmed by the above refining background,leaves significant technical and economic voids in the arena of crudeoils and turbine fuels. Such voids cause turbine designers to use the“what are available at lowest cost” liquids as turbine fuels when NG isunavailable or other alternatives cannot meet supply requirements, evenwhen such use causes corrosion, fouling, operability and emissionsproblems.

BRIEF SUMMARY OF THE INVENTION

We have discovered less complex methods and apparatus to convert crudeto a fuel useful as a turbine or engine fuel. We have also found that wecan produce a single liquid carbonaceous turbine fuel from crude insteadof extracting multiple products from crude in the manner of conventionalrefining complexities. We have found that fuel produced in accordancewith methods of this invention are useful in marine or land basedengines, combustion gas turbines, or fired heaters.

We have developed a paradigm shift in how clean fuels are made in thatwe economically separate crude based upon levels of sulfur content, notrigid temperature cut points or historic long standing standard multiplecut classifications. We make as few component cuts as possible and onlyfurther treat such few cuts, in such smallest numbers and amounts as ispractical to meet target fuel specifications for contaminate levels.Sulfur and metals targets for a fuel of this invention compriseregulatory requirements at location of firing, such as IMO(International Marine Organization) regulations for coastal and at seafiring by ships, and local emission regulatory authorities for landbased firings.

The polished turbine fuel (PTF) of this invention is a new compositionclass of crude derivative, having low levels corrosives, foulants, andother contaminants that are problematic for turbines and theenvironment. In lieu of direct firing crude in turbines, crude ispolished by this invention to efficiently remove noxious metals, sulfurand other contaminates to produce a single product turbine fuel. As usedin the specification and claims, “essentially free” or “essentiallymetal free” means a fuel comprising from nil (zero) up to 100 ppmwttotal metals. However, methods of this invention can produce fuels withonly trace metals content such as 100 ppbwt or less, and also mayinclude levels are which metals content, if any, can not be accuratelymeasured by on-line instruments.

Polished turbine fuel can compete with natural gas and diesel sincefiring polished turbine fuel increases turbine availability, reducesmaintenance cost, and reduces emissions over direct crude firing, witheffect approaching reliabilities and emissions levels attained by firingmany grades of natural gas or expensive diesel grades.

We have thus discovered that we can decontaminate crude in a tailored,extraordinarily efficient manner, to produce an ultraclean fuel suitablefor firing turbines.

This sole fuel product of crude is made with minimal unit operations andapparatus. The fuel is produced by a novel crude polishing process (CPP)herein described having a low cost apparatus configuration as a crudepolishing complex (CPC).

Thus, the practice of this invention enables lower capital and operatingcosts than conventional refinery complexes. The many additionalequipment and additional unit operations used in refining of crude toproduce multiple separate streams are eliminated by this inventionbecause a single product is produced.

However, CPC of this invention is clearly not a ‘topping refinery’, nora ‘hydroskimming refinery’, nor an ‘upgrading refinery’ (or “conversion”or “complex” refinery as discussed in above US EPA reference. All ofsuch refineries produce numerous hydrocarbon liquid products whereas CPPof this invention produces only one product fuel. The apparatusconfiguration of this invention is relatively simple and very differentthan conventional refining. Conventional refineries produce numerousstreams, only some of which are suitable for use as turbine fuels.Opposite thereto, with one or more crude feeds, the process of thisinvention uses novel apparatus to make only one liquid polished turbinefuel which is useful as a fuel product.

This invention does not require that all of the crude feed be convertedto turbine fuel. A certain amount of the crude may be use to generateutilities to operate the process. Since this invention provides a simpleway of isolating contaminates from crude and make polished turbine fuel,the invention leaves contaminant rich streams available for use as asource of energy to supply power for plant operations and for export.For example, an oxidization system may receive a portion of contaminantenriched streams within the process. Since such contaminant enrichedstreams have high fuel values, they can alternately be used for otherplant requirements. In addition to utilities, the process optionally canproduce sulfur as by-product.

The operating conditions of the different unit operations of thisinventive process can be adjusted based on crude hydrocarbon assay, orcombinations of crudes, or other alternative materials selected feed forthe operations, and sizing of each apparatus component is impacted byrespective throughputs and anticipated operating severities.

The polish turbine fuel of this invention is especially suited as areplacement fuel for utilities production facilities consuming crudeoil, residual oils, masut and/or high sulfur fuel oil (HSFO) configuredas simple cycle power plants (SCPP) and simple cycle power & waterplants (SCPWP) to enable more efficient operation with substantiallylower emissions.

Variations of the process of this invention can convert anysubstantially liquid carbonaceous source of material into usable liquidturbine fuel by directing various types of feeds into alternativelocations within the process complex of this invention. In onevariation, suitable carbon sources include combinations of differentcrude oils or a single crude with one or more residual oils or grades ofhigh sulfur fuel oil. In another variation, suitable carbon sources forsuch alternative feed locations include, for example a variation havinggasification apparatus fed with slurries of basis separation zonebottoms or vacuum residuals mixed with particles of coke, coal, peat orash from other operations. Also, optional carbon sources may includeslurries of biomass and include wood, canes, corn debris and urbanwaste.

Variations of embodiments of the crude polishing process of thisinvention are described by use of a single crude oil as an example feed;however, other embodiments of this invention may use one or more crudeoils or different contaminated hydrocarbonaceous liquids, either aloneor combined with one or more crude oil feeds. References herein to‘crude’ include contaminated crude oils, as well as other contaminatedheavy liquids, for illustration, not limitation, refinery residual oilsor high sulfur fuel oils. Contaminants may include compounds containingsulfur, nitrogen, oxygen as well as metals as complexes and salts.“Sulfur” as used herein means compounds containing the element, forillustration and not limitation, one or more compounds selected fromgroup consisting of thiols (RSH), sulfides (RSR′), polysulfides (RSSR′),thiophenic and alkyl-substituted isomers of thiophenic compoundscontaining various numbers of aromatic rings polycyclic aromatic sulfurheterocycles such as thiophene, benzothiophene, dibenzothiophene, andbenzonaphthothiophene and other sulfur containing hydrocarbons.

In this invention, operating conditions are controlled to set targetsbased upon sulfur or other contaminate levels of effluent streams, notby non-contaminant related performance criteria. Opposite thereto,conventional refinery distillation targets are different effluent streamproduct performance specifications for various specific differentapplications. Such conventional specifications, not related tocontaminants, include for example (i) for gasoline, vapor pressurerelated to volatility or octane for anti-knock, (ii) for No 2 diesel,cetane number for combustion speed, or flash point or distillationinitial boiling point or (iii) for kerosene, smoke point, flash point ortemperature of 10% distilled maximum or final boiling point.

In one embodiment, crude is fed to a basic separation unit (BSU). TheBSU can be a fractionating unit operation but the CPP's BSU differs fromprior art refinery atmospheric convention distillation units (CDU) inmany ways for several reasons. First, BSU splits the crude into onlythree basic segments based on target contaminate levels within (a)acceptable low level of contaminants, with a preference fordecontaminated to target level, depending of adjustment of BSU operatingconditions, (b) mildly contaminated, for illustration sulfur in therange of 0.08 to 4 wt. % and (iii) contaminate rich, for illustrationsulfur in the range of 2 to 8 wt. %. Opposite thereto, conventional CDUfractionates crude into numerous fractions based on target hydrocarboncompositions of the desired fractions or operating temperatures. Second,BSU operating conditions are controlled to set targets based uponcontaminate levels of effluent streams, not by non-contaminant relatedperformance criteria. In one embodiment, a liquid fuel having a lowlevel of contaminants suitable for use as a turbine fuel is a product ofthe process comprising (a) feeding a contaminated carbonaceous liquidfeed selected from the group consisting of one or more of crude oils,refinery residual oils, high sulfur fuel oils, biomass liquids, orhydrocarbon slurries containing particles of coke, coal, peat or ash toa basic separation zone which serves as a primary decontaminator, (b)separating said liquid feed in said zone into a minimum number of basicsegments based upon measurement of contaminate levels of effluentstreams, not based upon measurement of hydrocarbon composition,temperature range or other non-contaminant related separation criteria,(c) adjusting operating conditions of said separation zone to controlseparation of feed to form segments having different contaminate levelsto form (1) a reduced contaminate level segment, which withoutsubstantial subsequent treatment, forms a fuel component stream, (2) amildly contaminated segment which is treated by hydrogen in the presenceof catalyst to form one or more reduced contaminate level fuel componentstreams and (3) a contaminate rich segment which is subjected to one ormore additional separation steps to form one or more reduced contaminatelevel streams, each of which are treated, either separately or combined,by hydrogen in the presence of catalyst to form one or more reducedcontaminate level fuel component streams, and (d) combining fuelcomponent streams of c. (1), (2) and (3) to form said product fuel.

BRIEF DESCRIPTION OF THE DRAWINGS

The FIGURE is a schematic drawing of a process arrangement for treatmentof crude oil to produce a single liquid product useful as a turbine fuelin accordance with this invention.

DETAILED DESCRIPTION OF THE INVENTION

In one embodiment of this invention, a fuel is formed by combination ofthree liquid hydrocarbonaeous flowing streams derived from crudecomprising compounds of sulfur. In a preferred variation, the fuel isformed by substantial continuous combination of such streams as flowingstreams. As used in the specification and claims, “substantiallycontinuous” combining of flows means combining streams, either directlyfrom production units or from reserve storage of individual streams, ina manner to enable intermixing, and “flow rate” or “rate of flow”includes an amount of flow to a batch when stream flows are addedseparately. The flow rate of each stream to the combination isdetermined by its respective sulfur content and relative contribution tooverall final sulfur content limit of the combination, taking inconsideration flow rate of each of the other two streams and theirrespective sulfur content. In one variation, such streams are formed asprecursors for combination by fractionating crude, either with orwithout presence of added steam, into at least three liquid fractionsF1, F2, and F3 wherein yield cut, as wt. % of crude feed or othermeasurement of each fraction, is determined by its sulfur content suchthat the sulfur content of fraction F1 is less than that of fraction F2which is less than fraction F3. All or portions of fractions F2 and F3are subsequently treated with hydrogen in the presence of catalyst atconditions of temperature, hydrogen partial pressure, hydrogen flowrate, catalytic activity and space velocity sufficient to reduce sulfurcontent of such streams to at least target levels or below.

The first unit operation of this invention is a basic separation unit,consisting of one or more fractionators. Although preferably operated ator near atmospheric pressure in a preferred embodiment and havingdistillation capability, the first unit operation is different fromconventional refinery atmospheric crude distillation units which havemore stages inside the column and higher fractionation efficiency. Thenumber of side cuts and hence the rundown streams quantity and qualityare different with the basis separation units operations of thisinvention over typical crude distillation since the final product fromthe process of this invention is a single composition, a polishedturbine fuel.

The feed flash zone temperature of the first unit operation ispreferably designed to maximize the cut for fraction F2 while minimizingentrainment of heavy material and minimizing the amount of fraction F3from the bottom of the first unit. In preferred variations, the thirdfraction F3 is steam stripped in a stripping section of the first unitto minimize light ends entrainment in such third fraction F3 to avoidloading the vacuum overhead ejector system of the second fractionatorunit which operates under reduced pressure. In an illustration of onevariation of this invention, the overhead and side first fraction F1flow rate of the first fractionator is maximized by increasing firstfractionator boil-up so that fraction F1, becoming untreated stream S1for combination to the fuel, has a sulfur content in the range of 0.20wt. % sulfur, which exceeds the final fuel product sulfur limit whichwill preferably be less than 0.05 wt. %, or in the range of 0.05% to 0.1wt. %; however, in this variation, diluting flow rates of streams S2 andS3 with relatively low sulfur content are added the combination based onS1 sulfur level. Levels of sulfur of S3 liquids from vacuum gas oilhydrotreating can be less than 0.18 wt. % depending on severity ofconditions, but to avoid intense conditions causing ring saturation andloss of heating value, S3 preferably is in the range of 0.12 wt. % to0.18 wt. %. S2 from distillate hydrotreating can, for mild conditions,be readily less than 0.05 wt. %, yet for selected conditions known inthe hydrotreating art, S2 sulfur levels of less than 25 ppmwt can bereached and levels of less than 8 ppmwt can be reached, but preferableS2 is in the range of 6 to 12 ppmwt. Thus treated S2 and S3 are combinedwith untreated stream S in applicable amounts based on respective sulfurcontent so that final fuel combination meets product fuel specification.Process energy consumption in hydrotreaters treating fractions F2 and F3is reduced in relation to whatever amount of fraction F1 bypasses thehydrotreaters. Also, the minimization of side cuts or run downsminimizes the capital cost of the first and second fractionators.

Unlike conventional crude distillation, fractionation efficiency orsharpness of cuts is not a specification for the process or apparatus ofthis invention nor are multiple rundown streams since this invention isfor making a single finished fuel product from feed such as a crude, notmultiple products finely segregated by different boiling ranges. In oneembodiment of a fractionator of this invention, the fractionator has anupper, middle and lower zone for separating crude oil feed to respectivefractions F1, F2 and F3. Such fractionator does not achievefractionation efficiency for precise cuts based on temperature,hydrocarbon composition or other non-contaminant related separationcriteria but achieves separations based on contaminate levels of targetfractions F1, F2 and F3, either as one cut for each such fraction ormultiple cuts combined to form each such fraction. When suchfractionator is processing the same crude for a comparative toconventional crude oil distillations processing the same crude, thefractionator of this inventor can operate at a higher temperatureprofile in the upper zone. Such different temperature profile avoidsexcessive vapor condensation and flooding experienced in the uppersections of conventional crude oil distillation caused by sub-coolingand related pressure change upsets leading to condensation of strippingsteam, when used, and avoids excessive liquids formation and floodingthat can occur in conventional crude oil distillations. The fractionatorof this embodiment enables maximizing the quantity of fraction F1 withinsaid upper zone in relation to fractions F2 and F3, which fraction F1 ifwithin conventional distillation would include materials within therange from light overhead unstabilized whole naphtha to kerosene rangecomponents or at least a portion of other light distillates. Suchmaximization of fraction F1 would minimize quantity of light distillatesin fraction F2 reducing load on hydrotreating or other treatment offraction F2. It also enables combining all of such materials within therange from light overhead unstabilized whole naphtha to kerosene rangecomponents or at least a portion of other light distillates in fractionF1 into a single cut leading to fewer rundown systems over conventionalcrude oil distillation units that has multiple cuts for such rangematerials. Also, such fractionator maximizes quantity of fraction F2within said middle zone in relation to fraction F3, which fraction F2 ifwithin conventional distillation would include materials within therange from a portion of remaining heavier portion of light distillatesand middle and heavy distillates, which maximization enables combiningsaid remaining heavier portion of light distillates and middle and heavydistillates in fraction F2 in a single cut leading to fewer rundownsystems over conventional crude oil distillation units that has multiplecuts for such materials. Such fewer number of rundowns decreasespressure drop across the fractionator column due to reduced rundownstreams, and reduced number of trays, hence decreases the feed flashzone pressure, and hence decreases the flash zone temperature, withcorresponding reduction in column furnace duty which reduces energyconsumption compared to conventional crude distillation.

In one variation, fraction F1 is precursor for stream S1, fraction F2 isprecursor for stream S2, fraction F3 is precursor for stream S3, andstreams S1, S2 and S3 are combined to form a fuel, useful as a polishedturbine fuel, having a maximum 0.1 wt. % sulfur content and containsless than 100 ppmwt total metals, and more preferably 0.1 to 1.0 ppmwttotal metals. Preferred fractionation includes overhead partialcondensation of condensable entrained light gases to form at least aportion of fraction F1 but without need for added investment instabilization steps to remove butanes and other lighter components, withthe intent that condensable portions of liquefiable petroleum gases fromcrude source become part of the final fuel product. Addition of suchstabilization is a permitted variation, yet adds capital costs notessential for production for primary turbine fuel product. Preferablyyield cut of fraction F1 is maximized so that when fraction F1 is notsubsequent treated for sulfur removal or reduction but is combined withat least a portion of each fraction F2 and 3 which portions treated toremove or reduce sulfur content, the final sulfur content targetspecification or sulfur limit of the combination is not exceeded.Fraction F1 can be essentially free of sulfur, metals and othercontaminates or can contain relatively low levels of sulfur. In avariation, at least a portion of fractions 2 and 3 are each subsequentlytreated, by hydrotreating or other desulfurization means, to reducesulfur content so that each treated portion has a sulfur content of lessthan 50 ppmwt. In another variation, at least a portion of fractions 2and 3 are each subsequently treated, by hydrotreating or otherdesulfurization means, to reduce sulfur content so that treated fractionF2 has extremely low sulfur in the range of less than 10 ppmwt or lessand treated fraction F3 has higher sulfur than fraction F2 such as inrange of about 0.12 to 0.18 wt. %. Useful conventional hydrotreatingapparatus, catalyst, process configurations and conditions are discussedin Chapter 7 of Colorado School of Mines, Refining series, which oneskilled in the hydrotreating art may apply and adjust for hydrotreatingthe applicable portions of fractions 2 and 3 with hydrogen in thepresence of catalyst under hydrotreating conditions, and streams derivedfrom such fractions, in the practice of the hydrotreating aspects ofthis invention to achieve target stream S2 and S3 reduced sulfur andmetals contents.

In addition to sulfur, the crude may comprise other contaminantscontaining metals such as vandanium, nickel, lead, and zinc and othersthat cause corrosion or form foulants, as well as foulants ofasphaltenes families, and in variations of this invention, crude feedrate and fractionation conditions are adjusted such that substantiallyall such contaminates are concentrated in fraction F3. In one embodimentof this invention, fractionating conditions are adjusted such that (i)fraction F1 forms untreated stream S1 having sulfur content X1 and isessentially free of metals, (ii) fraction F2 when subsequently treatedwith hydrogen in the presence of catalyst under conditions adjusted toforms stream S2 having reduced sulfur content X2 and is essentially freeof metals. Fractionation includes overhead partial condensation ofcondensable entrained light gases but without added stabilization stepsto remove butanes and other lighter components, an extremely low levelof sulfur and almost nil level of other contaminants, and (iii) fractionF3, at least a portion of which when subsequently treated with hydrogenin the presence of catalyst under conditions more severe than thetreatment of fraction F2 to form stream S3 having significant reducedsulfur content X3 and has very low levels of metals. When suchhydrotreated streams 2 and 3 are combined with untreated stream S1, thecombination forms a fuel suitable for use as a polished turbine fuel,having a total sulfur content S_(T) and flow rate determined by flowrate of stream S of sulfur content X1, flow rate of stream S2 of sulfurcontent X2, and flow rate of stream S3 of sulfur content X3. In onevariation, fraction F1 has a sulfur content in the range of about 0.2wt. % to 0.25 wt. % to form stream S1, fraction F2 has a sulfur contentin the range of about less than 10 ppmwt after treating to form streamS2 and fraction F3 after treating forms stream S3 which has a sulfurcontent in the range of about 0.12 to 0.18 wt. %

In another variation, a fuel is formed by subjecting fraction F3, priorto hydrotreating, to vacuum distillation at reduced hydrocarbon partialpressures, either with or without presence of added steam, to form oneor more (i) light or heavy vacuum gas oil side streams, or combinationsthereof and (ii) vacuum residue which does not boil at said reducedpressures. One or more of said (i) light or heavy vacuum gas oil sidestreams, or combinations thereof may have a sulfur content in the rangeof about 0.1 to 5.0 wt. % prior to subsequent treating and are directedto hydrotreating and then are separately hydrotreated in a differentzone than fraction F2 and under more intense hydrotreating conditionsthan fraction F2 to form stream S3 has a sulfur content in the range ofabout 0.12 to 0.18 wt. % and which is essentially metal free or containssubstantially nil metal content of about 0.1 ppmwt. In an alternative,if the sulfur content of the lightest vacuum gas oil side stream hassulfur content less than or within the range of fraction F2 prior tosubsequent treating, then such gas oil stream can be combined withfraction F2 for subsequent treating and contribute to stream S2.

In one variation, the vacuum residue is directed to solvent deasphaltingwhere it mixed with one or more solvents, preferably paraffinic of 3 to7 carbon numbers, to enable precipitation out of solution asphaltenes orother residue heavy components to produce (i) one or more deasphaltedoils which have reduce levels of contaminants and (ii) a highlycontaminated pitch stream that contains the majority of metal,asphaltenes, and other contaminants of the original crude feed.

In a variation, at least one deasphalted oil stream is fed to thefraction F3 hydrotreater either separately or combined with one or moreof the vacuum gas oil side streams fed to fraction F3 hydrotreater, andis hydrotreated to form a portion of stream S3. When stream S3 so formedis combined with streams 1 and 2, a fuel useful as turbine fuel isformed. The pitch stream is useful as feed to delayed or continuouscoker, a gasification unit, or asphalt production. In a preferredvariation, the pitch stream is fed to a gasification unit which convertsthe pitch stream to synthesis gas consisting of hydrogen and carbonmonoxide and purifies the hydrogen which is directed to hydrogenation ofcomponents forming streams 2 and 3.

Various conditions of “mild conditions” of hydrotreating are describedin U.S. Pat. No. 6,228,254 to Jossens et al, and such term as usedherein means conditions of temperature, hydrogen partial pressure,hydrogen flow rate, catalytic activity and space velocity being adjustedsufficiently to reduce sulfur less to less than 50 ppmwt. More “severeconditions” of hydrotreating, and such term as used herein means whereconditions of temperature, hydrogen partial pressure, hydrogen flowrate, catalytic activity and space velocity are adjusted sufficient toreduce sulfur to much lower levels than mild conditions yet tosubstantially avoiding ring saturation. Considerations of sulfurcompound structure are discussed in “New Approaches to DeepDesulfurization for Ultra-Clean Gasoline and Diesel Fuels: An Overview”by Song, Fuel Chemistry Division Preprints 2002, 47(2), 439. Very deepsulfur removal may be possible by alternative routes discussed in “CleanFuels and Catalysis Program, The Energy Institute, and Department ofEnergy & Geo-Environmental Engineering”, by Xiaoliang Ma et al ThePennsylvania State University, AAD Document Control Center, M/S 921-107National Energy Technology Center, US Department of Energy Institute.However, “deep sulfur removal” level as used herein means wherehydrotreating conditions, whether mild or severe, include appropriatehydrogen quantity and partial pressure, are adjusted to reduce sulfurlevel to the range of 10 ppmwt or less. “Revamping Diesel HydrotreatersFor Ultra-Low Sulfur Using IsoTherming Technology” by Ackerson et aldiscusses unit design, catalyst choices, hydrogen consumption, and otheroperating conditions for sulfur removal by hydrogenation to produce aproduct containing less than 8 ppm sulfur by use of a high activityNi/Mo catalyst. “Optimizing Hydroprocessing Catalyst Systems forHydrocracking and Diesel Hydrotreating Applications, Flexibility ThroughCatalyst” by Shiflet et al, page 6 Advanced Refining TechnologiesCatalagram Special Edition Issue No. 113/2013 also discusseshydroprocessing to 10 ppm or less levels using high activity CoMocatalyst to remove unhindered sulfur and a high activity NiMo catalystfor remaining sterically hindered sulfur.

The FIGURE gives a general overview of another embodiment of thisinvention and shows in simplified form the major components of processoperation for production of a single liquid product suitable for use asa fuel. A stream of contaminated crude oil comprising sulfur and metalsenters the process via line 2 after pretreatment such as desalting,which is preferred for crude oil. In this example, the crude feed 2 canbe a single crude oil or blends of one or more crude oils or a blend ofa crude oil with high sulfur fuel oil.

Said crude is fractionated, with or without presence of added steam,into three liquid fractions F1, F2 and F3. In the embodiment shown inthe FIGURE, fraction F1 passes without treatment via line 10 tocombination zone 600. Fraction F2 passes via line 20 to hydrotreatingunit 300 to produce treated stream S2 which is directed via line 60 tocombination zone 600. Feed rate to and conditions of hydrotreating unit300 are adjusted so that treated steam S2 has a sulfur content less than10 ppmwt and a total metals content the range of less than 100 ppmwt orwhich is essentially metal free depending on severity of hydrotreating.Fraction F3 is directed via line 30 to an additional separation step invacuum fractionation unit 200. From basic separation unit 100, entrainedlight gases pass overhead via line 4 and overhead partial condensationof condensable entrained light gases occurs during fractionation withoutadded stabilization steps to remove butanes and other lighter componentsand pass via line 8 to combine with flows at line 10 to form a portionof fraction F1. The light hydrocarbon gases of line 4 from upper zone ofunit 100 may be concentrated via line 6, separated and distributed asneeded; for example, separated into wet gases (such as propane andbutane) or liquefied petroleum gas and dry gases (such as ethane andmethane) through a series of distillation columns and one or more ofsuch gases can be used to fire furnaces for other process unitoperations. Ancillary apparatus details are not shown but may include,for example, a reflux drum and associated water boot to remove thecondensing steam associated with the overhead contributed mainly fromstripping steam that optionally may have been fed to bottom zone of unit100 and any associated side strippers, and the reflux control apparatusfor adjustment of the temperature of the overhead temperature by use ofreflux sourced from such reflux drum. At line 10, fraction 1 includes afirst side cut drawn at lower stage at line 10 than the overhead stageat line 4 and 8 producing the overhead vapor, for example at lines 4 and6, which first cut is combined with condense overhead 8. Non-condensablelight gases pass overhead via line 6 where such may be recovered for useto furnace operations. In the variation shown in the FIGURE, basicseparation includes vacuum fractionation and fraction F3 is passed vialine 30 and subjected to vacuum distillation in unit 200 at reducedhydrocarbon partial pressures, either with or without presence of addedsteam, to form at least one vacuum gas oil effluent stream at line 40and to form at least one vacuum residual stream at line 50. To adjustsulfur levels, the fraction F3 in line 30 can be supplemented by ablending high sulfur fuel oil (not shown) and the vacuum residual streamat line 50 can be supplemented by a blending high sulfur fuel oil oralternative residual oil from another source, not shown.

In another variation (not shown), at least a portion of fraction F3 canbe directly passed to hydrotreater 400. In the variation shown in theFIGURE, the vacuum gas oil stream portion of Fraction F3 is directed vialine 40 to hydrotreating unit 400 and separately hydrotreated in adifferent zone than fraction F2 and under more intense hydrotreatingconditions than fraction F2 to form at least a portion of stream S3.Fractionating conditions of unit 200 are adjusted so that vacuum gas oileffluent stream at line 40 has a sulfur content in the range of about0.5 wt. % to 5 wt. % prior to subsequent treating in unit 400.Hydrotreated portion of Fraction F3 is directed via line 70 to becomepart of hydrotreater effluent stream S3 that is directed via line 70 tocombination zone 600. Feed rates to and hydrotreating conditions of unit400 are adjusted for stream S3 to have a sulfur content in the range ofabout 0.12 to 0.18 wt. % and a total metals content the range of aboutless than 0.1 ppmwt to 1 ppmwt, which is within essentially metal free.The vacuum fractionation unit 200 also forms a vacuum residue effluentstream portion of Fraction F3 at line 50 which does not substantiallyboil at said reduced hydrocarbon partial pressures and is directed vialine 50 to solvent deasphalting unit operation 500. In the FIGURE, thevacuum residue is mixed in unit 500 with one or more solvents to form asolution in a manner that enables precipitation out of said solutionmuch of the asphaltenes and other residue heavy components to form (1) ahighly contaminated pitch stream at line 90 that contains the majorityof metals of the original contaminated crude oil feed, which is directedvia line 90 to other uses or disposal and (2) a substantially solventsoluble deasphalted oil at line 80 which has reduced asphaltene contentand a total metals content the range of not less than about 2 ppmwt andnot more than 20 ppmwt is passed via line 80 to hydrotreater 400 andhydrotreated to form treated portion of fraction F3 that forms at leasta portion of stream S3. In one variation (not shown) high sulfur fueloil or other heavy residual oil is added to the solvent separation unit,either alone or with the vacuum residue.

In fractionating unit 100, yield cut, as wt. % of crude feed 2 or othermeasure, of each fraction F1 at line 10, F2 at line 20 and F3 at line 30is determined by its sulfur content such that sulfur content of fractionF1 at line 10 is less than that of fraction F2 at line 20 which is lessthan sulfur content of fraction F3 at line 30. Also, by adjustingoperation conditions of fractionating units 100 and 200 substantiallyall metals are concentrated in the portion of fraction F3 at line 50.Yield cut of fraction F1 at line 10 is maximized based on sulfur contentof the combination product stream 600 made by combining flows of (i) theportion of fraction F2 which is hydrotreated to reduce sulfur content toless than about less than 10 ppmwt to form stream S2 at line 60 and (ii)the one or more portions of fraction F3 at lines 40 and 80 which arehydrotreated in zone 400 to form stream S3 at line 70 having reducedsulfur content of less than about 0.12 to 0.18 wt. % and (iii) untreatedfraction F1 having a sulfur content less than about 0.2 to 0.25 to formstream S1 at line 10 to combination 600 where the final sulfur contentof the combination 600 of streams S1 of line 10, S2 of line 60 and S3 ofline 70 does not exceed total sulfur content limit specification ortarget of said fuel. Suitable online measuring devices for rapidanalysis of sulfur content are commercially available, for illustrationnot limitation, such as “EDXRF/XRF for Sulfur” and others available fromApplied Rigaku Technologies, Inc., Austin, Tex., which measures rangesof 0.02 to 6.0 wt. % sulfur.

In one variation of this embodiment, the sulfur content of fraction F1at line 10 is measured to ensure it does not exceed its operatingspecification limit, and fraction F1 is directed, without furthertreatment, as stream S1 in line 10 continuously to the combination zone600. Also, the sulfur content of untreated streams at lines 20 and 30are measured. For illustration, after measuring the sulfur content offraction F3 at line 30, fraction F3 can directed to one or moreadditional separation zones 200 and 500 to separate fraction F3 by oneor more process steps into two or more portions, each of which portioncan be subsequently treated for sulfur removal, with treatment type andseverity being select based upon feed sulfur content. In anothervariation, sulfur content of streams 40 and 80 are measured andhydrotreating conditions of units 300 and 400 are adjusted to producetreated stream S2 at line 60 having a target sulfur content of less than10 ppmwt, preferably in the range of about 5 to 10 ppmwt, and treatedstream S3 at line 70 having a target sulfur content of less than 0.18wt. % in the range of about 0.12 to 0.18 wt. %. Steams S1 at line 10, S2at line 60, and S3 at line 70 are substantially continuous combined insaid combination zone 600 in a manner so that the (i) flow rate of eachstream to the combination is determined by its respective sulfur contentand related contribution to overall final sulfur content target limit ofthe combination, taking into consideration flow rate of each of theother two streams and their respective sulfur content; and (ii)fractionation unit 100 yield cut of untreated fraction F1 is maximizedin a manner whereby the final sulfur content limit of the combination atline 600 is not exceeded.

In a variation also illustrated by the FIGURE, the yield cut of fractionF1 is maximized to enable reduction of flow rates of fractions F2 and F3and corresponding loads on hydrotreating units 300. Crude feed rate 2,fractionating conditions at units 100 and 200, and relative effluentflow rates of fractions F1, F2 and F3 are adjusted so that when fractionF1 is not subsequently treated for sulfur removal or reduction but iscombined with treated portions of each fraction F2 and F3, whichportions are treated to remove or reduce sulfur content in units 300 and400 to form treated streams S2 at line 60 and S3 at line 70, the finalsulfur content target specification or sulfur limit of the product fuelat line 600 of combined streams S1, S2, and S3 is not exceeded. Ifsulfur content of final fuel combination 600 is exceeded or targetsulfur limit for fraction F1 for use in combination when consideringsulfur content and flow rates of steams S2 and S3, then eitherconditions of fractionating unit 100 or 200 or subsequent treatingconditions, whether of hydrotreating units 300 or 400 or alternativetreating unit 500 by solvent separation, are adjusted, depending onwhich condition adjustments are most economical to achieve sulfur levelsat or lower than interim and final target sulfur specification limits,such as a final fuel product total sulfur content limit of about 0.05 to0.1 wt. %. Alternatively, if sulfur content of fraction F1 causes finalproduct 600 sulfur content to approach or exceed its sulfur limit, aportion of fraction F1 or one of the side cuts forming fraction F1 canbe directed from line 10 via line 14 to hydrotreating unit 300 andhydrotreated to return overall final product sulfur content 600 to itstarget. In a preferred variation hydrotreaters 300 and 400 each havedemetallization materials or a guard bed which are sized as known bypersons skilled in the art. The objective of such guard bed is tocapture, reduce or impair contaminants and reduce the corrosive effectand ash deposition caused by oil-soluble trace metals that contribute toash formation at combustion.

The FIGURE also illustrates another variation in which vacuumdistillation at 200 separates fraction F3 at line 30 into two portionsat line 40 and line 50 and one of such portions at 50 is furtherseparated by solvent separation unit 500 into two additional portions atlines 80 and 90. The portions of fraction F3 at lines 40 and 80 aredirected to hydrotreating zone 400 and hydrotreating conditions of 400are adjusted for such portions to produce treated stream S3 having asulfur content in the range of about 0.12 to 0.18 wt. %. The treatedportions are combined or directed via line 70 to the combination zone600 as part of stream S3. The contaminant rich remaining portions offraction F3 forming pitch stream 90 which is not hydrotreated and isdirected via line 90 to alternative processing such as downstream unitsfor hydrogen, power or other utilities generation or other uses such asin asphalt.

In a preferred variation when the crude comprises contaminantscontaining asphaltenes, the crude feed rate 2 and fractionationconditions of units 100 and 200 or alternative separation processconditions of unit 500 such as solvent separation or deasphalting areadjusted such that substantially all such asphaltenes or other residualcontaminated are concentrated in remaining portions of fraction F3 atline 90 which portion is not directed to hydrotreating to avoid foulingor other adverse impact on hydrotreating catalyst. Also, forhydrotreating considerations, portion of fraction F2 can be directed vialine 44 to hydrotreating zone 400 to form part of stream S3 at line 70.Preferably the pitch stream 90 is used as feed to a gasification unit,or asphalt production, or a boiler. In one variation, portions offraction F3 which are not hydrotreated, whether as a heavy residual oilor a heavier pitch resulting from solvent deasphalting are used as feedto a gasification unit which converts such to synthesis gas consistingof CO and hydrogen, which hydrogen is then purified and directed tohydrogenation in zones 300 and 400 of portions of fractions F2 and F3forming streams S2 at line 60 and S3 at line 70. In variations,gasification unit operations can include acid gas treatment steps torecover molten sulfur as a byproduct and a combined cycle power plant touse synthesis gas in production of electricity.

Other variations of the embodiment illustrated in the FIGURE are part ofthis invention. In one variation, the fractionation unit 100 can havemultiple cuts or rundowns forming fraction F1 in line 10, or multiplerundowns forming fraction F2 in line 20 or rundowns and bottoms streamsforming fraction F3 in line 30.

Such multiple cuts or rundowns forming fraction F1 can be takeneconomically whereby they contain essentially no metals and very smalllevel of sulfur and nitrogen compared to the rest of the cuts from thebasic separation zones or fractionating units 100 and 200, and withoutfurther processing can be sent directly to the finished product stream600. For illustration, not limitation, adjusting fractionatingconditions of units 100 or 200, or both, to maximize the amount of upperzone low level contaminate or decontaminated fraction F1 minimizes theamount of low boiling portions of the contaminated midrange fraction F2load on hydrotreater 300 while maximizing the high boiling portion of F2fraction to minimize F3. Such adjustment facilitates a single side cutfor fraction F2 leading to less rundown systems and lower costs overmultiple cuts.

As illustrated by the FIGURE, in this invention, one target liquid fuelis the product of crude feed. Opposite thereto, in conventional crudeoil distillation units as part of a full-fledged refinery, there arenumerous products and related numerous distillation specificationsrequiring more trays to achieve fractionation efficiency essential toachieve such numerous product cuts and specifications. Sincefractionation efficiency is not a focus of importance of this invention,the fractionators of this invention do not need as many trays to achievebasic rough cut separation or fractionation, and thus may have lesstrays as well as less complex and less costly trays. Fewer separationtrays corresponds shorter column height and fewer required cuts, allleading to lower capital cost. By operating the process and apparatus ofthis invention for maximization of first fractionator upper zonequantity within fraction F1, versus that in upper zones of conventionalcrude distillation, would include materials that with conventionaldistillation would be lighter overhead unstabilized whole naphtha and aportion of heavier kerosene components, which bypasses subsequenthydrotreating or other treatment. Such broad range within fraction F1enables for the same processed crude as a comparative, a highertemperature profile in the upper zone for the first fractionator of thisinvention as compared to a conventional crude oil distillation unitstower. Another advantage of such higher temperature profile of thisinvention is that such avoids condensation experienced in the uppersections of conventional crude columns caused by sub-cooling andpressure upsets leading to stripping steam condensing in the upperstages of conventional crude columns. In addition, capital investment isfurther reduced by avoiding costs of naphtha stabilization columns. Suchhigher temperature profile in the upper zone enables different cuts ofthe crude in lower fractionating zones. When compared to conventionaldistillation, for example, maximizing in fraction F1 a portion of whatmight otherwise fall within lighter kerosene range materials wouldminimize amount of light distillates and enable combining remaininglight, middle and heavier distillates range materials in fraction F2 ina single cut leading to fewer rundown systems and lower costs overconventional crude oil distillation units that has multiple cuts. Also,having a higher temperature profile of first fractionation unit enableseliminating or minimizing rundown streams and their associated pumparound systems and pump around associated trays by combining mid-rangesulfur containing cuts. For example, hydrocarbon streams that mightotherwise be within conventional ranges of a heavier kerosene rangematerials, light distillate, middle and heavier distillate of conventioncrude distillation, may be combined into one common cut as fraction F2,and such reduces the equipment list of the first fractionator andfurther reduces capital cost turbine fuel product. By dropping thenumber of side cuts and the pump around associated with them we decreasepressure drop across the fractionator column due to reduced rundownstreams, and hence the feed flash zone pressure, and hence the flashzone temperature, with corresponding reduction in column furnace dutywhich reduces energy consumption compared to conventional crudedistillation.

Preferred final fuel product contains 0.1 wt. % sulfur or less, but suchfuel sulfur content can be adjusted by unit operations to be more orless. The sulfur removal by the combined unit operations as illustratedin the FIGURE can be much lower than 0.1 wt. % sulfur, or to meet marketneeds for fuels having a sulfur content in excess of 0.1 wt. % sulfursuch those for marine applications ranging from 3.5 wt. % sulfur orlower. Fuel sulfur content adjustments may be made by adjusting unitoperations of this inventive process based on either allowable sulfurfeed content limits or sulfur emission levels from turbine systemsfiring fuels of this invention or corrosion issues of such turbinesusing such fuels.

Although the various embodiments of the invention have been described,it is to be understood that they are meant to be illustrative only andnot limiting. It is apparent that the present invention has broadapplication to production of fuels having low levels of sulfur and othercontaminants. Certain features may be changed without departing from thespirit or scope of the present invention. Accordingly, the invention isnot to be construed as limited to the specific embodiments or examplesdiscussed but only as defined in the appended claims or substantialequivalents of the claims.

1-10. (canceled)
 11. A method to convert a contaminated crude oil (2)comprising sulfur and metals, with or without presence of added feedsteams, to a fuel having a sulfur content limit characterized in thatthe crude is fractionated into three liquid fractions F1 (10), F2 (20),and F3 (30, 40) and at least a portion of fraction F2 (60) and a portionfraction F3 are hydrotreated (70) wherein fractionating (100, 200) andhydrotreating (300, 400) conditions are adjusted such that: a. overheadpartial condensation of condensable entrained light gases (4) occursduring fractionation (100) without added stabilization steps to removebutanes and other lighter components to form a portion of fraction F1(8, 10), b. each fraction of crude is determined by its wt. % sulfurcontent such that sulfur content of fraction F1 (10) is less than thatof fraction F2 (20) which is less than fraction F3 (30), c.substantially all metals are concentrated in fraction F3 (30); d. yieldcut of fraction F1 (10) is maximized based on sulfur content of acombination product stream made by combining flows of (i) a portion offraction F2 (20) which is hydrotreated (300) to reduce sulfur content toless than 25 ppmwt to form stream S2 (60) and (ii) portions of fractionF3 (40, 80) which are hydrotreated (400) to reduce sulfur content toless than 0.12 to 0.18 wt. % to form stream S3 (70) and (iii) untreatedfraction F1 having a sulfur content less than 0.25 wt. % to form streamS1 (10) where the final sulfur content limit of the combination (600) ofstreams S1 (10), S2 (20) and S3 (30) does not exceed total sulfurcontent limit of said fuel.
 12. A method in accordance with claim 11wherein, prior to hydrotreating any portion of fraction F3,substantially all of fraction F3 is subjected to vacuum distillation atreduced hydrocarbon partial pressures, either with or without presenceof added steam, to form: a. at least one vacuum gas oil effluent stream(40) having a sulfur content, % mass of crude, in the range of about 0.1wt. % to 5 wt. % prior to subsequent treating, which stream is directedto hydrotreating (400) and hydrotreated in a different zone thanfraction F2 hydrotreater (300) and under more intense hydrotreatingconditions than fraction F2 to form at least a portion of stream S3 (70)which has a sulfur content in the range of 0.12 wt. % to 0.18 wt. % andcontains less than 1 ppmwt metals; and b. a vacuum residue effluentstream (50) which does not substantially boil at said reducedhydrocarbon partial pressures which residue is directed to solventdeasphalting (500) and mixed with one or more solvents to form asolution in a manner that enables precipitation out of said solutionasphaltenes and other residue heavy components to form: (i) a highlycontaminated pitch stream (50) that contains the majority of metals ofthe original contaminated crude oil feed; and (ii) a deasphalted oil(80) that forms a portion of stream S3 (70) and is either (A) combinedwith a non-hydrotreated portion of fraction F3 and such combination ishydrotreated to form at least a portion of stream S3 or (B) hydrotreatedand combined with a separately hydrotreated portion of fraction F3 toform at least a portion of stream S3.
 13. A method in accordance withclaim 11 comprising: a. measuring the sulfur content of fraction F1 andwithout further treatment, directing fraction F1 continuously to saidcombination, b. measuring the sulfur content of fraction F2 anddirecting fraction F2 to a hydrotreating zone and adjustinghydrotreating conditions for fraction F2 to produce treated stream S2having a sulfur content of less than 10 ppmwt and directing treatedstream S2 continuously in all or in part to said combination zone, c.measuring the sulfur content of fraction F3 and directing fraction F3 toa separation zone to separate fraction F3 by one or more process stepsinto two or more portions, (i) first portion which is to be hydrotreatedwhich are directed to a hydrotreating zone and adjusting hydrotreatingconditions for such portions to produce treated stream S3 having asulfur content of less than 0.18 wt. % and directing treated stream S3continuously to said combination zone and (ii) second portions which arenot hydrotreated. d. continuously combining steams S1, S2, and S3 insaid combination zone, wherein (i) flow rate of each stream to thecombination is determined by its respective sulfur content and relatedcontribution to overall final sulfur content limit of the combination,taking in consideration flow rate of each of the other two streams andtheir respective sulfur content; and (ii) yield cut of untreatedfraction F1 is maximized in a manner whereby the final sulfur contentlimit of the combination is not exceeded;
 14. A method in accordancewith claim 11 wherein the crude comprises contaminants containingasphaltenes and crude feed rate and fractionation conditions areadjusted such that substantially all such asphaltenes are concentratedin last portion of fraction F3 which is not hydrotreated.
 15. A methodin accordance with claim 11 wherein said pitch stream is used as feed toa gasification unit, boiler, or asphalt production.
 16. A method inaccordance with claim 11 wherein said pitch stream is used as feed to agasification unit which converts the pitch to synthesis gas consistingof CO and hydrogen, which hydrogen is directed to hydrogenation ofportions of fractions F2 and F3 forming streams S2 and S3.
 17. A fuelproduced in accordance with the process of claim 11 having a sulfurcontent limit selected at or below regulatory requirements at locationof firing.
 18. A fuel produced by the method of claim 11 formed bycombination of steams S1, S2 and S3 which is useful as a polishedturbine fuel having a maximum 0.1 wt. % sulfur content and less than 0.1ppmwt metals content.
 19. Use of a fuel produced in accordance with theprocess of claim 11 in marine or land based engines, combustion gasturbines, or fired heaters. 20-22. (canceled)